ECM standard vs auto ??

[85k5dsl]

I just completed my TBI motor swap and I'm very pleased, it runs well and no check engine light. The ECM is from a truck with a auto tranny and I run a standard, after I drive around for awhile and come to a stop it will stay on high idle for a min to two and then idle normal. Is this due to the ECM being from a automatic truck?

Thanks

 

[dave w]

I just completed my TBI motor swap and I'm very pleased, it runs well and no check engine light. The ECM is from a truck with a auto tranny and I run a standard, after drive around for awhile and coming to a stop it will stay on high idle for a min to two and then idle normal. Is this due to the ECM being from a automatic truck?

Thanks

Congratulations on getting the TBI motor swap done.

I can think of some reasons the high idle continues (based on personal experience).
The swap did not include a vehicle speed sensor?
The park / neutral switch wire needs to be set to chassis ground (battery negative) to eliminate the need for a vehicle speed sensor.
The IAC minimum air setting needs to be adjusted?

dave w

 

[85k5dsl]

Dave,
Your are correct no VSS, I'll ground the park wire and see what happens before I mess with the IAC.

Thanks

 

[dave w]

Dave,
Your are correct no VSS, I'll ground the park wire and see what happens before I mess with the IAC.

Thanks

Usually the Park / Neutral wire is Orange with a Black Stripe. In the schematics it's labeled Org/Blk.

One other thing to check the TPS voltage.

dave w

 

[eagle mark]

It's probably one of the points Dave made do to the conversion.

But the manual trans chip is differant then an auto. Most of the differences are in the IAC logic do to shifting. But most manuals don't have a Park/Neutral wire if the harness also came from a manual, at least ones I have pulled and used. It is more dependent on VSS for idle control.

 

[85k5dsl]

The harness also came from the gas truck, I did have a 6.2 diesel. Thanks for the replies.

 

[eagle mark]

Getting that Park/Neutral wire done will help since it is an Auto chip. Adding a VSS also will help. But getting a manual chip or even recording some data so someone can burn a fine tuned chip will be a very nice addition.

Congrats on the swap and welcome to EFI world!

 

[GMC Truck]

I had problems with my conversion till I added the VSS then most of my problems went away. I currently have the factory style on my truck now (in back of cluster) but there is one that just screws onto the speedometer cable output and these work very well and are the simplest to wire up.